Want to Generate Energy? Go Fly a Kite

More than 200 years ago, Benjamin Franklin advanced the research of electricity by flying a kite. Now, a German company is taking a slightly different tack on that old idea by using kites to generate energy.

Nature Technology Systems (NTS) GbH has designed a principle based on the same elements of energy output, speed, and consistency used in wind turbines, according to the company. The result is a method that uses clusters of kites to form an aerial power station 1,000 feet to 2,000 feet in the air that produces energy on the ground.

The system, which NTS is testing in collaboration with the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart, works like this:
The kites fly at high altitudes, where there are strong winds, on a tether of cables about 2,000 feet in length that's connected to vehicles on the ground, said Joachim Montnacher, an engineer at the IPA, in a press release. Those vehicles are pulled around a circuit on rails, producing kinetic energy that is then turned into electricity by a generator. The vehicles include the control and measuring mechanisms for the energy generated.

One of the test kites being used to create energy according to a method designed by Nature Technology Systems in Germany makes its first flight. The company -- which partnered with Fraunhofer Institute for Manufacturing Engineering -- said the system it created uses the same principles as wind turbines but is more efficient and environmentally friendly. (Source: Fraunhofer Institute for Manufacturing Engineering and Automation IPA)

Specifically, the kites generate the energy through buoyancy achieved when a kite flies in high wind speed, according to NTS. Anyone who has ever flown a kite will know that the pull of the kite increases the faster the kite flies. NTS's design of the system allows the kite to surpass a buoyancy of about 110 lb/22 ft. "So when we fly a 20m2 (215 ft) sized kite it will be able to drag and lift up to 1 ton in weight," the company explained on its Website.

NTS insists its kite energy farms are more efficient, economical, and environmentally friendly than wind turbines. Because typical wind turbine rotors max out at a height of about 650 feet, they can't take advantage of winds at higher elevations, which are stronger. "Depending on wind conditions, eight kites with a combined surface area of up to 300 square meters (about 3,200 feet) can equate to 20 conventional 1 megawatt wind turbines, Montnacher said.

The kites also avoid material and financial investment in wind turbine infrastructure, which has more of an impact on the environment.

NTS will continue to test its kite system and will reveal its findings and seek feedback from the energy industry once these tests are complete, the company said.

The Germans aren't the only ones taking to the skies to find new and different ways to use wind and air currents to create alternative sources of energy. The US military recently tested a method to fly aircraft in formation that would promote fuel efficiency by using vortex surfing, a technique similar to what bicycle racers and migrating birds do when they cluster together to draft off each other.

Am I missing something? How could the generator car possibly "loop back" when the kites are pulling in a vector that probably won't vary by more than 45 degrees? Assuming a long narrow oval track at 90 degrees to the wind, on the straight legs of the oval the kites would only be providing a portion of the total force anyway: moving the generator first to the left, say, on the up wind straight leg, then following the wind direction through the first curve, then the kite would have to tack to the right, pulling the generator to the right on the downwind straight leg, then it would get to the next curve, somehow proceed against the kite force and midway through the curve the kite needs to reverse tack to the left, the generator still working against the kite to get back to the straight leg. If this works they've discovered perpetual motion.

Unlike solar farms or windmills which are inherently difficult to look at or follow with the eyes, advertisers could use these kites to place their logos on truly unobstructed billboards, and not cut down any trees in the process. So capitalism could serve environmentalism for a change. And vice versus.

Of course, the kites would have to fly in a public area, but those are the small details. : )

A close view of the picture shows four lines going to the kite. This might imply that that 4 lines are needed for strength and or redundancy. However, it also implies that the kite would be capable of being directionally controlled (tacking) allowing it to fly in directions not directly downwind. Nothing mandates that a track mounted generator can't store enough power to propel itself while tacking crosswind down a track perpendicular to the wind for the brief period needed to navigate the half loop at the end of an oval track. Then there's the design study needed to show if a figure 8 track (allowing more downwind travel) of a given distance would provide more net power than an oval track with a given diameter at the ends.

I think the only solution for aircraft concerns would be to ban aircraft from the area entirely. This is especially true since in the US, aviation is moving away from flight paths to routes decided by pilots through GPS tracking.

This is not unprecedented. There are many areas off limits to aircraft already.

It does remind me a bit of barrage balloons during Word War II I read about.

Excellent points about aircraft concerns. Lights could be one option; however, I'm sure as this system continues to get tested this will be addressed. One easy solution would be to try to put them in areas where there aren't often low-flying craft. Staying far away from airports is an obvious solution to that.

I didn't want to say anything from an aviation standpoint, because that's something I'm a little biased on. Since the door's been opened, I think it's outrageously dangerous to have a kite above 1000' AGL. Yes, there are antennas that reach that high with nice, bright beacons, and one can assume that the kite would be as well lit, but the problem with a kite is that you have no way of knowing where the aluminum shredding tether is going to be. There was a story similar to this before, and I likened the tethered, airborne windmill to a WWII era barrage balloon, and certainly, the effect to a passing aircraft would be similar.

I wonder if they've thought about potential aircraft collisions. In Illinois, where I live, it's very easy to spot wind turbines at night because wind farms typically have synchronized red lights that blink on and off at night. Could they do the same with kites?

Liz, thanks for covering this--what fun, how elegant, and I like the lower environmental impact of the technology. While most wind turbines don't go as high, the one we wrote about herehttp://www.designnews.com/document.asp?doc_id=243636is designed to eventually achieve over 1,000 feet in altitude.

It might be very similiar to model rocketry protocol - waivers sometimes have to be filed and approved with the FAA and flight patterns have to meet certain criteria. That would probably be a good way to deal with air traffic. We wouldn't want a model rocket crashing through one of those kites!

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